Vulnerable Systems:
* Mozilla Firefox 17.0
* Mozilla Thunderbird 17.0
* Mozilla SeaMonkey 2.14
* Mozilla Firefox ESR 10.0.11
* Mozilla Thunderbird ESR 10.0.11
Multiple Mozilla products contain a user-after-free error in the ~nsHTMLEditRules() function. This issue may allow a context-dependent attacker to dereference already freed heap memory and potentially execute arbitrary code.